Method and device for controlling transmission power in uplink transmission

ABSTRACT

A user equipment in wireless communication system is provided. The user equipment includes an antenna unit including a plurality of antennas, a control unit for grouping the plurality of antennas into a predetermined number of antenna groups and controlling separately transmission power of each of the predetermined number of antenna groups, and a transmitting unit, connected to the control unit, for transmitting at least one of data and control information to a base station via at least one of the predetermined number of antenna groups.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 13/203,471, filed on Aug. 25, 2011, now U.S. Pat. No. 8,977,312, which is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2010/001176, filed on Feb. 25, 2010, which claims the benefit of earlier filing date and right of priority to Korean Patent Application No. 10-2010-0015218, filed on Feb. 19, 2010 and also claims the benefit of U.S. Provisional Application Nos. 61/220,511, filed on Jun. 25, 2009, 61/169,699, filed on Apr. 15, 2009, 61/161,414, filed on Mar. 19, 2009, 61/161,420, filed on Mar. 19, 2009, 61/157,863, filed on Mar. 5, 2009, 61/155,519, filed on Feb. 26, 2009, and 61/155,493, filed on Feb. 25, 2009, the contents of which are all hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a method and device for controlling transmission power in uplink transmission.

BACKGROUND ART

The major objectives of power control are to guarantee a required received signal to noise ration (SNR) by compensating path-loss and fading of channel and to provide a high system throughput with proper link adaptation. In addition, inter-cell interference can be also handled by power control. In the 3rd generation partnership project (3GPP) long term evolution (LTE) system, the uplink power control is based on open-loop power control with closed-loop correction. The open-loop power control is handled by a user equipment (UE) and the closed-loop correction is done by an evolved Node B (eNB). FIG. 1 shows basic concept of uplink power control in LTE system.

As shown in FIG. 1, the uplink power is mainly measured by UE in open-loop manner and the eNB can adjust the uplink power by closed-loop correction factor Δ.

The exact formula can be expressed as the following Math Figure 1. P _(PUSCH)(i)=min{P _(MAX), 10 log₁₀(M(i))+P _(o)(j)+α(i)·PL+Δ _(TF)(i)+f(i)} [dBm]  [Math Figure 1]

In Math Figure 1, at a time index i, the P_(MAX) denotes the maximum allowed power, and it depends on the UE class. In addition, M(i) is decided according to allocated resource blocks which can varied from 1 to 110 and it is updated in every subframe. The α·PL is used as path loss compensation term where PL denotes downlink path-loss estimated by UE and is scaling value. The αis equal to and less than 1 and is expressed as 3 bit value. If α=1 is satisfied, path loss is fully compensated and If α<1 is satisfied, path loss is fractionally compensated.

In addition P_(O)(j) is calculated as the following Math Figure 2. P _(O) =P _(O) _(_) _(CELL) _(_) _(SPECIFIC) +P _(O) _(_) _(UE) _(_) _(SPECIFIC)   [Math Figure 2]

In the Math FIG. 1, f(i) is UE-specific parameter controlled by the eNB. In addition, the power control for Physical Uplink Control Channel (PUCCH) can be defined as the following Math Figure 3. P _(PUCCH)(i) =min{P _(MAX) , P ₀ _(_) _(PUCCH) +PL+h(n _(CQI) ,n _(HARQ))+Δ_(F) _(_) _(PUCCH)(F)+g(i)} [dBm]  [Math Figure 3]

The parameter Δ_(F) _(_) _(PUCCH)(F) is provided by higher layers. Each Δ_(F) _(_) _(PUCCH)(F) value corresponds to a PUCCH format (F) relative to PUCCH format 1a. In addition, h(n) is a PUCCH format dependent value, where n_(CQI) corresponds to the number information bits for channel quality information (CQI) and n_(HARQ) is the number of hybrid automatic repeat request (HARQ) bits.

For PUCCH format 1,1a and 1b, the following Math Figure 4 is satisfied. h(n _(CQI) ,n _(HARQ))=0   [Math Figure 4]

For PUCCH format 2, 2a, 2b and normal cyclic prefix, the following Math Figure 5 is satisfied.

$\begin{matrix} {{h\left( {n_{CQI},n_{HARQ}} \right)} = \left\{ \begin{matrix} {10\;{\log_{10}\left( \frac{n_{CQI}}{4} \right)}} & {{{if}\mspace{14mu} n_{CQI}} \geq 4} \\ 0 & {otherwise} \end{matrix} \right.} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 5} \right\rbrack \end{matrix}$

In addition, for PUCCH format 2 and extended cyclic prefix, the following Math Figure 6 is satisfied.

$\begin{matrix} {{h\left( {n_{CQI},n_{HARQ}} \right)} = \left\{ \begin{matrix} {10\;{\log_{10}\left( \frac{n_{CQI} + n_{HARQ}}{4} \right)}} & {{{{if}\mspace{14mu} n_{CQI}} + n_{HARQ}} \geq 4} \\ 0 & {otherwise} \end{matrix} \right.} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 6} \right\rbrack \end{matrix}$ P_(O) _(_) _(PUCCH) is a parameter composed of the sum of a cell specific parameter P_(O) _(_) _(NOMINAL) _(_) _(PUCCH) provided by higher layers and a UE specific component P_(O) _(_) _(UE) _(_) _(PUCCH) provided by higher layers.

δ_(PUCCH) is a UE specific correction value, also referred to as a Transmission Power Control (TPC) command, included in a PDCCH with DCI format 1A/1B/1D/1/2A/2 or sent jointly coded with other UE specific PUCCH correction values on a PDCCH with DCI format 3/3A whose CRC parity bits are scrambled with TPC-PUCCH-RNTI.

In addition to PUCCH and PUSCH, Sounding Reference Signal (SRS) is also power controlled as the following Math Figure 7. P _(SRS)(i)=min {P _(MAX) , P _(SRS) _(_) _(OFFSET)+10 log₁₀(M _(SRS))+P _(O) _(_) _(PUSCH)(j)+α·PL+f(i)} [dBm]  [Math Figure 7]

In the Math Figure 7, P_(SRS) is UE transmission power for SRS transmitted on subframe i.

For K_(S)=1.25, P_(SRS) _(_)OFFSET is a 4-bit UE specific parameter semi-statically configured by higher layers with 1 dB step size in the range [−3, 12] dB.

In addition, for K_(S)=0, P_(SRS) _(_) _(OFFSET) is a 4-bit UE specific parameter semi-statically configured by higher layers with 1.5 dB step size in the range [−10.5,12] dB. Here, the Ks is a parameter for turning on or turning off Δ_(TF)(i), where Δ_(TF)(i) is a parameter for controlling power of PUCCH.

M_(SRS) is the bandwidth of the SRS transmission in subframe i expressed in number of resource blocks.

f(i) is the current power control adjustment state for the PUSCH.

P_(O) _(_) _(PUSCH)(j) is a value composed of sum of cell-specific power control parameter and UE-specific power control parameter, which are configured by higher layers.

FIG. 2 illustrates general uplink transmitter structure in LTE system. AS shown in FIG. 2, only one antenna port transmission is allowed in uplink LTE system and in a time, single channel of PUCCH and PUSCH can be transmitted.

DISCLOSURE OF INVENTION Technical Problem

The uplink power control is handled with whole UE transmission power due to single power amplifier (AMP) UE structure. However, if a UE employs multiple power AMPs, single power control factor may cause a significant problem in 2 Tx antenna case since power imbalance problem can happen due to a specific situation of handset (e.g., hand gripping). Therefore, appropriate power control mechanism should be designed for 2 Tx antenna case.

Meanwhile, PUSCH and PUCCH have their own power control factors as P_(PUCCH)(i) and P_(PUSCH)(i).

In addition, each channel can transmit maximum transmit power P_(MAX) in LTE system since both channels are never transmitted at the same time. However, if it is allowed to transmit both PUSCH and PUCCH at the same time, appropriate power sharing should be designed to enable simultaneous transmission of PUSCH and PUCCH in the advanced system (e.g., LTE-A).

Solution to Problem

Accordingly, the present invention is directed to a user equipment in wireless communication system, the user equipment including an antenna unit including a plurality of antennas; a control unit for grouping the plurality of antennas into a predetermined number of antenna groups and controlling separately transmission power of each of the predetermined number of antenna groups; and a transmitting unit, connected to the control unit, for transmitting at least one of data and control information to a base station via at least one of the predetermined number of antenna groups.

Preferably, the user equipment may further include a receiving unit for receiving information about turn-on or turn-off of each of the predetermined number of antenna groups.

Preferably, the antenna unit may include four antennas and the turn-on and the turn-off of each of the predetermined number of antenna groups may be configured as an index.

Also, there is a user equipment in wireless communication system, the user equipment including a control unit for controlling a maximum transmission power of Physical Uplink Control Channel (PUCCH) and a maximum transmission power of Physical Uplink Shared Channel (PUSCH); and a transmitting unit, connected to the control unit, for transmitting the PUCCH and the PUSCH simultaneously. The control unit controls the maximum transmission power of PUCCH to be higher than the maximum transmission power of PUSCH.

Preferably, when P_(MAX) denotes a maximum transmission power of the user equipment, P_(MAX,PUCCH) denotes the maximum transmission power of the PUCCH and P_(MAX,PUSCH) denotes the maximum transmission power of the PUSCH, P_(MAX)=a*P_(MAX, PUCCH), P_(MAX)=b*P_(MAX), a+b=1 and 1=a>0.5 may be satisfied.

Also, there is a user equipment supporting a plurality of uplink transmission bandwidths in wireless communication system, the user equipment including a control unit for controlling maximum transmission power of the plurality of uplink transmission bandwidths; and a transmitting unit, connected to the control unit, for transmitting the plurality of uplink transmission bandwidths to a base station. A primary maximum transmission power for transmitting a primary uplink transmission bandwidth among the plurality of uplink transmission bandwidths is allocated firstly from a maximum power of the user equipment and remaining transmission power of the maximum power of the user equipment is allocated to remaining uplink transmission bandwidths.

Preferably, each of the remaining uplink transmission bandwidths is determined by subtracting a corresponding offset value from the primary maximum power.

Advantageous Effects of Invention

According to the present invention, uplink transmission power can be saved in user equipment. In addition, uplink channels can be effectively can be transmitted.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.

In the drawings:

FIG. 1 shows basic concept of uplink power control in LTE system.

FIG. 2 illustrates general uplink transmitter structure in LTE system.

FIG. 3 shows two uplink power control types in case of 2 Tx antennas according to the present invention.

FIG. 4 shows three uplink power control types in case of 4 TX antennas according to the present invention.

FIG. 5 illustrates an uplink power control types in case of 4 TX antennas according to the present invention.

FIG. 6 shows an example of multi component carriers used for a UE.

FIG. 7 is a block diagram showing constitutional elements of a device performing a method of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention, rather than to show the only embodiments that can be implemented according to the invention. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without such specific details. For example, the following description will be given centering on specific terms, but the present invention is not limited thereto and any other terms may be used to represent the same meanings.

Hereinafter, multiple power control mechanism of the present invention can be employed for handling power imbalance between multiple antennas in the uplink.

FIG. 3 shows two uplink power control types in case of 2 Tx antennas according to the present invention. In 2Tx, as shown in FIG. 3, uplink power control types can be considered. In type-A of FIG. 3, both transmission antennas always transmit the same power irrespective of power imbalance for the sake of simplicity. In this case, fine control of each transmit antenna cannot be allowed so power waste in a UE can be expected due to coarse power adjusting.

The type-B shows that power control is performed for each of the two antennas in uplink. Power saving in uplink is one of key features since it is closely related to battery efficiency. Therefore, by adjusting power for each of antennas, it would be possible to save more transmit power at a UE. For example, the power of the second antenna P₂ can be controlled by delta offset to the power of the first antenna P₂, i.e., P₂=P₁+Δ_(offset).

In this case, different type of power control can be employed according to uplink channel. The following Table 1 shows a combination of power control of PUSCH and PUCCH in case of 2 TX antennas.

TABLE 1 PUSCH PUCCH Case-A Type-A Type-A Case-B Type-A Type-B Case-C Type-B Type-A Case-D Type-B Type-B

Meanwhile, 4 Tx antennas can be employed in UE. FIG. 4 shows three uplink power control types in case of 4 TX antennas according to the present invention.

The type 1 shows the same power transmission across all the transmission antennas. This type has the least complexity and control overhead. However, power saving performance would be worst among the three types due to its coarse power adjustment. To improve the performance, group-wise power control can be used in which two antenna groups from four antenna ports have its own power control factor as shown in type-2 in FIG. 4. An antenna group may have one or higher number of antenna ports and the other antenna port belongs to the other antenna group in this case. Antenna power control can be also used for 4 Tx antennas to provide better power saving performance. In this case, different type of power control can be employed according to the uplink channel as shown in the following Table 2.

TABLE 2 PUSCH PUCCH Case-1 Type-1 Type-1 Case-2 Type-1 Type-2 Case-3 Type-1 Type-3 Case-4 Type-2 Type-1 Case-5 Type-2 Type-2 Case-6 Type-2 Type-3 Case-7 Type-3 Type-1 Case-8 Type-3 Type-2 Case-9 Type-3 Type-3

In Table 1 and Table 2, several cases are mentioned for 2Tx and 4Tx antenna ports. Among the cases, the following Table 3 can be considered as appropriate case as an exemplary from the optimal tradeoff between control signaling overhead and power saving performance.

TABLE 3 2Tx 4Tx Ex-1 Case-A Case-1 Ex-2 Case-A Case-4 Ex-3 Case-A Case-5 Ex-4 Case-C Case-1 Ex-5 Case-C Case-4 Ex-6 Case-D Case-1 Ex-7 Case-D Case-5 Ex-8 Case-D Case-9

Each transmission antenna has its own maximum power P_(MAX) as shown in Math Figure 1 and the maximum power depends on the UE class. Therefore, the maximum power is fixed in the UE perspective. If the P_(MAX) is allowed to be configured by the eNB, antenna power imbalance problem can be solved easily and the eNB has an ability to turn on/off a specific transmit antenna port at a UE if multiple power control factor is employed.

As in type-B in FIG. 3, P₁ and P₂ can be used for per antenna based power control. In that case, in general, P₁ and P₂ have same P_(MAX) under the assumption that same physical antenna and power AMP are employed for each transmit antenna port and the P_(MAX) is fixed value. Here, each antenna port cannot transmit power higher than P_(MAX). Therefore, by allowing configurable P_(MAX) for each transmit antennas, flexible power control is possible in the uplink.

Let P_(1,MAX) and P_(2,MAX) be maximum power for P₁ and P₂, respectively. Then, multiple values for P_(1,MAX) and P_(2,MAX) can be used so as to allow flexible power control. The multiple values can be expressed as α₁P_(1,MAX) and α₂P_(2,MAX), where α₁ and α₂ has several values including ‘0’ and ‘1’. If α₁=0 is used for an antenna port, which implies that the corresponding antenna port is turned off.

This can also be applied for type-3 in FIG. 5 in the same manner. In addition, P_(1,MAX) and P_(2,MAX) can be fixed value per UE or UE class.

If two or more number of power control factor are used according to the type, the power can be separately defined according to the uplink channel. Let P₁ and P₂ be the power control factors for each transmit antenna and/or antenna group. The P_(MAX) can be defined as following Table 4 when multiple channels (e.g., PUSCH and PUCCH) are transmitted at the same time.

TABLE 4 P_(MAX) P_(MAX) = P_(1,MAX) + P_(2,MAX) P_(1,MAX) P_(1,MAX) = P_(1,PUSCH,MAX) + P_(1,PUCCH,MAX) P_(2,MAX) P_(2,MAX) = P_(2,PUSCH,MAX) + P_(2,PUCCH,MAX) Type-P P_(1,PUCCH,MAX) = P_(2,PUCCH,MAX) = P_(PUCCH,MAX)/2P_(1,PUSCH,MAX) = P_(1,MAX) − P_(1,PUCCH,MAX)P_(2,PUSCH,MAX) = P_(2,MAX) − P_(2,PUCCH,MAX) Type-Q P_(1,PUSCH,MAX) = P_(2,PUSCH,MAX) = P_(PUSCH,MAX)/2P_(1,PUCCH,MAX) = P_(1,MAX) − P_(1,PUSCH,MAX)P_(2,PUCCH,MAX) = P_(2,MAX) − P_(2,PUSCH,MAX)

In addition, the P_(MAX) can be defined as following Table 5 when PUCCH and SRS are transmitted at the same time.

TABLE 5 P_(MAX) P_(MAX) = P_(1,MAX) + P_(2,MAX) P_(1,MAX) P_(1,MAX) = P_(1,SRS,MAX) + P_(1,PUCCH,MAX) P_(2,MAX) P_(2,MAX) = P_(2,SRS,MAX) + P_(2,PUCCH,MAX) Type-P P_(1,PUCCH,MAX) = P_(2,PUCCH,MAX) = P_(PUCCH,MAX)/2P_(1,SRS,MAX) = P_(1,MAX) − P_(1,PUCCH,MAX)P_(2,SRS,MAX) = P_(2,MAX) − P_(2,PUCCH,MAX) Type-Q P_(1,SRS,MAX) = P_(2,SRS,MAX) = P_(SRS,MAX)/2 P_(1,PUCCH,MAX) = P_(1,MAX) − P_(1,SRS,MAX)P_(2,PUCCH,MAX) = P_(2,MAX) − P_(2,SRS,MAX)

Furthermore, the P_(MAX) can be defined as following Table 6 when PUSCH and SRS are transmitted at the same time.

TABLE 6 P_(MAX) P_(MAX) = P_(1,MAX) + P_(2,MAX) P_(1,MAX) P_(1,MAX) = P_(1,SRS,MAX) + P_(1,PUSCH,MAX) P_(2,MAX) P_(2,MAX) = P_(2,SRS,MAX) + P_(2,PUSCH,MAX) Type-P P_(1,PUSCH,MAX) = P_(2,PUSCH,MAX) = P_(PUSCH,MAX)/2P_(1,SRS,MAX) = P_(1,MAX) − P_(1,PUSCH,MAX)P_(2,SRS,MAX) = P_(2,MAX) − P_(2,PUSCH,MAX) Type-Q P_(1,SRS,MAX) = P_(2,SRS,MAX) = P_(SRS,MAX)/2 P_(1,PUSCH,MAX) = P_(1,MAX) − P_(1,SRS,MAX)P_(2,PUSCH,MAX) = P_(2,MAX) − P_(2,SRS,MAX)

In addition, the P_(MAX) can be defined as following Table 7 when PUSCH, PUCCH and SRS are transmitted at the same time.

TABLE 7 P_(MAX) P_(MAX) = P_(1,MAX) + P_(2,MAX) P_(1,MAX) P_(1,MAX) = P_(1,SRS,MAX) + P_(1,PUSCH,MAX) + P_(1,PUCCH,MAX) P_(2,MAX) P_(2,MAX) = P_(2,SRS,MAX) + P_(2,PUSCH,MAX) + P_(2,PUCCH,MAX) Type-P P_(1,PUCCH,MAX) = P_(2,PUCCH,MAX) = P_(PUCCH,MAX)/2P_(1,PUSCH,MAX) = P_(2,PUSCH,MAX) = P_(PUSCH,MAX)/2P_(1,SRS,MAX) = P_(1,MAX) − (P_(1,PUCCH,MAX) + P_(1,PUSCH,MAX))P_(2,SRS,MAX) = P_(2,MAX) − (P_(2,PUCCH,MAX) + P_(2,PUSCH,MAX)) Type-Q P_(1,PUCCH,MAX) = P_(2,PUCCH,MAX) = P_(PUCCH,MAX)/2 P_(1,SRS,MAX) = P_(2, SRS,MAX) = P_(SRS,MAX)/2 P_(1,PUSCH,MAX) = P_(1,MAX) − (P_(1,PUCCH,MAX) + P_(1,SRS,MAX))P_(2, PUSCH,MAX) = P_(2,MAX) − (P_(2,PUCCH,MAX) + P_(2,SRS,MAX))

Even though the relationships are defined for multiple power control factors for each antenna ports and/or each antenna groups, same rules can be applied for single power control factor for whole antenna ports.

UE informs its maximum transmittable power for each transmission antenna ports such as P_(1,UE,MAX) and P_(2,UE,MAX) where the former indicates the maximum transmittable power of first antenna port and/or first antenna group and the latter indicates that of second antenna port and/or antenna group. From this reports, the eNB can choose each antennas and/or each antenna groups maximum power P_(1,MAX) and P_(2,MAX)

The power control factor can be switched across the antenna port. Let A_(i),i=0, . . . , N_(t)−1 be i-th antenna port, then power control factors P_(i) in type-B of FIG. 3 can be mapped as the following Table 8.

TABLE 8 Switching Power control factor mapping off {A₀:P₀}, {A₁:P₁} on {A₀:P₁}, {A₁:P₀}

This switching can be configured by eNB or done by UE request. The switching can be more complicated for 4Tx case. The type-2 in FIG. 4 can be defined according to the switching rule shown in the following Table 9.

TABLE 9 Switching Power control factor mapping off {AG₀:P₀}, {AG₁:P₁} on {AG₀:P₁}, {AG₁:P₀}

In Table 9, AG_(i), i=0,1 indicates antenna groups in which four antenna ports are separated to two groups.

FIG. 5 illustrates an uplink power control types in case of 4 TX antennas according to the present invention. The number of antenna ports in each group can be different as shown in FIG. 5.

The antenna ports in an AG₁ can be changed according to time, frequency or uplink channel and UE class. The following Table 10 shows an exemplary antenna grouping.

TABLE 10 Antenna grouping Ex-1 AG₀:{A₀,A₁}, AG₁:{A₂,A₃} Ex-2 AG₀:{A₀, A₂}, AG₁:{A₁,A₃} Ex-3 AG₀:{A₀}, AG₁:{A₁,A₂,A₃} Ex-4 AG₀:{A₁}, AG₁:{A₀,A₂,A₃} Ex-5 AG₀:{A₂}, AG₁:{A₀,A₁,A₃} Ex-6 AG₀:{A₃}, AG₁:{A₀,A₁,A₂}

To have multiple power control factors such as P₁ and P₂, only UE specific correction value can have multiple values such as f₁(i),g₁(i) for P₁ and f₂(i), g₂(i) for P₂, and the others are shared across the power control factors since the UE specific correction value is a closed-loop power control handled by an eNB so that more precise power adjustment is possible.

Abovementioned power control type can vary in time in a UE point of view and may be configured by eNB in semi-static manner.

According to the UE class, the number of power control factor can be different with same number of antenna port.

Each power control factors P, can includes zero power transmission, that is, antenna turn off, so that only specific antenna and/or antenna group can transmit power. This can be controlled by several ways as the following.

Each antenna or antenna group may have its own maximum transmission power limitation such as P_(1,max) and P_(2,max) and the maximum transmission power can be controlled by on/off factor which is configured by the eNB. The on/off control factor can be expressed as α0 and β.

These control factors may have only two values that is ‘0’ or ‘1’ and the value ‘0’ indicates turning off corresponding antenna, thereby four cases can be defined as Table 11 and Table 12.

TABLE 11 index Description 00 α = 0, β = 0 both antennas or antenna groups are turned off, thereby no uplink transmission. (Silent mode) 01 α = 0, β = 1 first antenna or antenna group is turned off. 10 α = 1, β = 0 second antenna or antenna group is turned off. 11 α = 1, β = 1 full antenna transmission (normal transmission mode)

TABLE 12 index Description 00 α = 0, β = 0 Reserved for other purpose 01 α = 0, β = 1 first antenna or antenna group is turned off. 10 α = 1, β = 0 second antenna or antenna group is turned off. 11 α = 1, β = 1 full antenna transmission (normal transmission mode)

A specific power control factor controlled by eNB may force a UE to turn off a specific antenna or antenna group in order not to waste transmission power.

Meanwhile, SRS is used to estimate channel information at an eNB side, therefore each antenna should transmit reference signal. However, due to higher signaling overhead, the eNB can request SRS for a specific antenna or antenna group. This may be used with antenna turn off mechanism mentioned above. The 2 bit indication can be used to support four types of SRS request for 2Tx and 4Tx transmission antenna case. For 2Tx case, SRS transmission can be classified as Table 13.

TABLE 13 indication Description 00 Silent mode or reserved 01 First antenna only transmits SRS 10 Second antenna only transmits SRS 11 Both antenna transmit SRS

In addition, for 4Tx case, the following Table 14 can be considered.

TABLE 14 indication Description 00 Silent mode or reserved 01 First antenna group only transmits SRS 10 Second antenna group only transmits SRS 11 Both antenna group transmit SRS

In Table 14, antenna group can be configured as shown in FIG. 4 and FIG. 5, for example. However, it is not limited to FIG. 4 and FIG. 5.

Hereinafter, a power control method for transmitting PUSCH and PUCCH simultaneously will be described.

The Math Figures 1 and 3 can be represented as following Math Figures 8 and 9 for the sake of simplicity, respectively. P _(PUSCH)(i)=min{P _(MAX) ,P _(PUSCH) ^(required)(i)} [dBm]  [Math Figure 8]

In Math Figure 8, P_(PUSCH) ^(required) can be P_(PUSCH) ^(required)(i)=10 log₁₀(M_(PUSCH)(i))+P_(O) _(_) _(PUSCH)(j)+α(j)·PL+Δ_(TF)(i)+f(i) if the same power control method is used for advanced system (e.g., LTE-A). Therefore, in general, P_(PUSCH) ^(required) implies that required transmission power to reach the error requirement and it can be designed by any other method. P _(PUCCH)=min{P _(MAX) ,P _(PUCCH) ^(required)(i)} [dBm]  [Math Figure 9]

In Math Figure 9, P_(PUCCH) ^(required) can be P_(PUCCH) ^(required)(i)=P_(O) _(_) _(PUCCH)+PL+h(n_(CQI),n_(HARQ))+Δ_(F) _(_) _(PUCCH)(F)+g(i), however, it is not restricted to the Math Figure 3 as well. Therefore, P_(PUCCH) ^(required) also simply implies required transmission power to meet the received SNR requirement and can be designed by several ways.

In addition to PUSCH and PUCCH, SRS power control factor also can be simplified as the following Math Figure 10. P _(SRS)(i)=min{P _(MAX) ,P _(SRS) ^(required)(i)}  [Math Figure 10]

In Math Figure 10, the P_(MAX) is the maximum allowed transmission power and configured by higher layer signaling. Therefore, to transmit both PUSCH and PUCCH simultaneously, the P_(MAX) should be shared by both channels. In this case, several types of power sharing can be considered.

Hereafter, P_(MAX) ^(PUSCH) and P_(Max) ^(PUCCH) denote maximum allowed transmission power for PUSCH and PUCCH, respectively. Therefore, P_(MAX)=P_(MAX) ^(PUSCH)+P_(MAX) ^(PUCCH) should be satisfied in simultaneous transmission case. In the other cases such as PUCCH only transmission or PUSCH only transmission, P_(MAX)=P_(MAX) ^(PUSCH)=P_(MAX) ^(PUCCH) can be used.

The P_(MAX) can be evenly shared for both PUSCH and PUCCH. In this case, the power sharing relationship can be expressed as P _(MAX) ^(PUSCH) =P _(MAX) ^(PUCCH) =P _(MAX)/2.

This even power sharing can be simplest power sharing method since the maximum power is divided by two and no additional signaling is needed.

In general, the control channel (i.e., PUCCH) requires higher reliability compared to traffic channel (i.e., PUSCH) since an error in control channel more seriously degrades system throughput as compared with that in traffic channel. Therefore, PUCCH channel can be prioritized to spend more transmission power. If control channel is well designed to reach an error requirement without full power transmission, the traffic channel prioritized power sharing method also can be considered. The following Math FIG. 11 denotes prioritized power sharing method.

$\begin{matrix} \left\{ \begin{matrix} {P_{MAX}^{PUSCH} = {\frac{\alpha}{\alpha + \beta}P_{MAX}}} \\ {P_{MAX}^{PUCCH} = {\frac{\beta}{\alpha + \beta}P_{MAX}}} \end{matrix} \right. & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 11} \right\rbrack \end{matrix}$

In Math Figure 11, α and β are a rational number which is equal to or larger than ‘0’ and satisfies the condition α+β=1.

If α>0.5 is satisfied, the PUSCH can have higher maximum power and PUCCH can have higher maximum power in the other case.

Meanwhile, the PUCCH transmission can be guaranteed by allowing maximum power transmission as P_(MAX) ^(PUCCH)=P_(MAX).

The maximum transmission power for PUSCH transmission can be defined as the following Math Figure 12. P _(MAX) ^(PUSCH)(i)=P _(MAX) −P _(PUCCH)(i)   [Math Figure 12]

In this case, the P_(MAX) ^(PUCCH) may be configured by higher layer and P_(MAX) ^(PUSCH) can be calculated by UE as the P_(PUCCH)(i) value get changed in time.

If PUSCH transmission is guaranteed, the power allocation method mentioned above can be switched between PUSCH and PUSCH. In this case, the maximum power transmission for PUSCH can be P_(MAX) ^(PUSCH)=P_(MAX) and the Math Figure 12 should be changed into Math Figure 13. P _(MAX) ^(PUCCH)(i)=P _(MAX) −P _(PUSCH)(i)   [Math Figure 13]

Meanwhile, the P_(MAX) ^(PUSCH) and the P_(MAX) ^(PUCCH) can be configured separately by higher layer signaling. In this case, separate maximum transmission power should be informed to a UE such as PUSCH only transmission, PUCCH only transmission and simultaneous transmission for more efficient power allocation as the following Table 15.

TABLE 15 Maximum allowed transmission power PUCCH only P_(MAX) ^(PUCCH only) PUSCH only P_(MAX) ^(PUSCH only) Simultaneous Transmission P_(MAX) ^(PUSCH) and P_(MAX) ^(PUCCH)

Meanwhile, in PUCCH transmission, several types of information are included such as Acknowledgement/Negative Acknowledgment (ACK/NACK), Channel Quality Information (CQI), Rank Information (RI) and Precoding Matrix Index (PMI). Even in PUCCH transmission, ACK/NACK should be strongly protected when multiple uplink channel transmission is possible in a same subframe. In addition to ACK/NACK, RI also needs to be protected. Therefore, when at least one of ACK/NACK and RI is transmitted, the following UE behavior can be defined.

In the first type, other uplink channels including PUSCH and SRS are not allowed to be transmitted.

In the second type, PUCCH is first guaranteed and if there is remaining power, the remaining power is shared with the other channels. In this case, the information such as CQI and PMI cannot be guaranteed.

Meanwhile, if unbalanced power allocation is employed for simultaneous transmission of PUSCH and PUCCH, according to allowed maximum power, one of the uplink channels can be dropped if the allowed maximum power is not exceed a certain level of power. For instance, when threshold level is set to P_(Threshold) as a reference, a UE can check whether maximum allowed transmission power is higher than P_(Threshold) and if P_(MAX) ^(PUSCH) and P_(MAX) ^(PUCCH) is lower than P_(Threshold), dropping corresponding channel at a time.

Abovementioned maximum allowed transmission power P_(MAX) ^(PUSCH) and P_(MAX) ^(PUCCH) can be shared with multiple antennas if multiple P_(MAX) ^(PUSCH) and/or P_(MAX) ^(PUCCH) are employed for better supporting multiple transmit antennas.

Meanwhile, if multi-carrier is employed for a single UE, the P_(MAX) should be shared for multi-carrier as well.

First, a description is given of the concepts of the term multi-carrier and the term component carrier. Multi-carrier indicates a total frequency band that is used by the UE and has the same meaning as whole band.

The component carrier is one of the component carriers that constitute the multi-carrier. That is, a plurality of component carriers constitutes a multi-carrier through carrier aggregation. Each component carrier includes a plurality of lower bands. Here, when the term multi-carrier is replaced with whole band, the aggregation of component carriers may be referred to as bandwidth aggregation. The term lower band, which indicates a sub-band, may be replaced with partial band. The carrier aggregation aggregates a plurality of carriers to extend the bandwidth in order to increase the data rate. For example, the conventional system uses 20 MHz as one carrier, whereas the system of the present invention aggregates five 20 Mhz carriers to extend the bandwidth up to 100 MHz. The carrier aggregation includes aggregation of carriers that are located in different frequency bands.

FIG. 6 shows an example of multi component carriers used for a UE. In FIG. 6, each component carrier can be regarded as independent physical channel (PHY) or LTE channel.

Let the P_(MAX) be a maximum allowed transmission power in uplink for whole component carriers aggregated and the number of component carrier can vary according to time in a UE perspective. For instance, if the number of the uplink component carrier (N_(comp)) for a UE can vary from 1 to 5 (i.e., 1≦N_(comp)≦5), then the P_(MAX) can be shared by N_(comp) component carriers. For the multiple component carriers, followings can be considered.

The maximum allowed power P_(MAX) can be equally shared by N_(comp) component carriers. Therefore, each component carrier may have P_(MAX)/N_(comp) maximum allowed power. In addition, each component carrier may have same or different P_(MAX) ^(PUSCH) and P_(MAX) ^(PUCCH) ratio for simultaneous transmission.

Among N_(comp) component carriers, one component carrier can be set as a primary carrier (called as anchor carrier as well), and used for transmitting prioritized information such as control channel, system information and etc. In this case, the primary carrier should be prioritized to provide more reliable system performance. The maximum allowed transmission power in primary carrier can be P_(MAX).

The remained power P_(MAX) ^(remained)(i)=P_(MAX)−P_(primary) ^(required)(i) is shared with the other component carriers. In this case, the P_(MAX) ^(remained)(i) can be also shared evenly between the remaining component carriers. In addition, the P_(MAX) ^(remained)(i) can be used for secondary carrier which is used for transmitting prioritized information next to the primary carrier.

In addition, even though whole required power cannot be allocated to primary carrier, higher power also can be allocated to primary carrier. In this case, primary carrier can be reference carrier for power sharing information such as P_(MAX) ^(primary)(i),

the other component carrier power sharing information can be informed with minus delta offset of primary carrier such as

P _(2,MAX)(i)=P _(MAX)(i)−Δ_(offset)

where Δ_(offset) is satisfying Δ_(offset)≧0.

The P_(MAX) for each component carrier can be configured by higher layer signaling. Full flexibility can be supported in this case. However, complexity and control signaling overhead can be higher than the other methods mentioned above. This can be indicated by delta offset from reference carrier. If three component carriers are employed for a UE, P_(1,MAX), P_(2,MAX) and P_(3,MAX) can be each component carriers maximum transmission power. If P_(1,MAX) is the reference carrier, P_(2,MAX)=P_(1,MAX)−Δ_(2,offset) and P_(3,MAX)=P_(1,MAX)−Δ_(3,offset) can be informed to a UE.

Δ_(i,offset) may have a value having a predetermined range including ‘0’.

Meanwhile, weighted power sharing is also possible for multiple component carriers. The following Math FIG. 14 shows weighted power sharing for multiple component carriers.

$\begin{matrix} \left\{ \begin{matrix} {P_{1,{MAX}} = {\alpha_{1}P_{MAX}}} \\ {P_{2,{MAX}} = {\alpha_{2}P_{MAX}}} \\ \vdots \\ {P_{N_{comp},{MAX}} = {\alpha_{N_{comp}}P_{MAX}}} \end{matrix} \right. & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 14} \right\rbrack \end{matrix}$

In Math Figure 14, α₁+α₂+ . . . +α_(N) _(Comp) =1 is satisfied.

In addition, each component carrier can have separate P_(i,MAX), i=1, . . . , N_(comp) and the P_(i,MAX) can be shared with two or more uplink channels at a time and it can be also used for a single uplink channel. When P_(i,MAX) is shared with two or more uplink channels such as PUCCH, PUSCH and SRS, the power sharing can be prioritized. Among three channels, PUCCH could be most important since misdetection of control channel may harm system performance seriously. The PUUCH can be prioritized as the following Math Figure 15.

$\begin{matrix} {P_{MAX}^{PUCCH} = {\sum\limits_{i = 1}^{N_{comp}}\; P_{i,{MAX}}^{PUCCH}}} & \left\lbrack {{Math}\mspace{14mu}{Figure}\mspace{14mu} 15} \right\rbrack \end{matrix}$

In Math Figure 15, all component carrier's P_(MAX) ^(PUCCH) is guaranteed as same as P_(i,MAX) ^(PUCCH)=K,i=1, . . . , N_(comp), where K is a certain value to be used for PUCCH channel. The other uplink channels shares the remaining power.

FIG. 7 is a block diagram showing constitutional elements of a device 100, that can be either a UE or an eNB, and that can perform the methods described above. Device 100 includes a processor 101, a memory 102, a radio frequency (RF) unit 103, a display unit 104, and a user interface unit 105. Layers of the radio interface protocol are implemented in the processor 101. The processor 51 provides the control plane and the user plane. The function of each layer can be implemented in the processor 101. The processor 101 may also include a contention resolution timer. The memory 102 is coupled to the processor 101 and stores an operating system, applications, and general files. If device 100 is a UE, the display unit 104 displays a variety of information and may use a well-known element such as a liquid crystal display (LCD), an organic light emitting diode (OLED), etc. The user interface unit 105 can be configured with a combination of well-known user interfaces such as a keypad, a touch screen, etc. The RF unit 103 is coupled to the processor 51 and transmits and/or receives radio signals.

The embodiments described above are provided by combining constituent elements and features of the present invention in specific forms. The constituent elements or features of the present invention may be considered optional if not explicitly stated otherwise. The constituent elements or features may be implemented without being combined with other constituent elements or features. The embodiments of the present invention may also be provided by combining some of the constituent elements and/or features. The order of operations in the embodiments of the present invention may be changed. Some constituent elements or features of one embodiment may be included in another embodiment or may be replaced with corresponding constituent elements or features of another embodiment. It is apparent that the present invention may be embodied by a combination of claims which do not have an explicit cited relation in the appended claims or may include new claims by amendment after application.

The embodiments of the present invention have been described focusing on the data communication relationship between an eNB and a UE. Here, the eNB refers to a terminal node of a network communicating directly with the UE. In some cases, a specific operation described as being performed by the eNB may be performed by an upper node of the eNB.

Namely, it is apparent that the eNB or any other network nodes may perform various operations for communication with the UE in a network comprised of a plurality of network nodes including the eNB. The term eNB may be replaced with the term fixed station, Node B, access point, etc. The term UE corresponds to a mobile station (MS) and the MS may be replaced with the term subscriber station (SS), mobile subscriber station (MSS), mobile terminal, etc.

The UE employed in the present invention may be a personal digital assistant (PDA), a cellular phone, a personal communication service (PCS) phone, a global system for mobile (GSM) phone, a wideband code division multiple access (wide CDMA) phone, a mobile broadband system (MBS) phone, etc.

The embodiments of the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof.

In a hardware configuration, methods according to the embodiments of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

In a firmware or software configuration, methods according to the embodiments of the present invention may be implemented in the form of modules, procedures, functions, etc. which perform the above-described functions or operations. Software code may be stored in a memory unit so as to be driven by a processor. The memory unit is located at the interior or exterior of the processor and may transmit data to and receive data from the processor via various known means.

The present invention may be embodied in other specific forms than those set forth herein without departing from the spirit and essential characteristics of the present invention. The above description is therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by reasonable interpretation of the appended claims and all changes coming within the equivalency range of the invention are intended to be embraced in the scope of the invention.

Mode for the Invention

The embodiments of the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof.

In a hardware configuration, methods according to the embodiments of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

In a firmware or software configuration, methods according to the embodiments of the present invention may be implemented in the form of modules, procedures, functions, etc. which perform the above-described functions or operations. Software code may be stored in a memory unit so as to be driven by a processor. The memory unit is located at the interior or exterior of the processor and may transmit data to and receive data from the processor via various known means.

The present invention may be embodied in other specific forms than those set forth herein without departing from the spirit and essential characteristics of the present invention. The above description is therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by reasonable interpretation of the appended claims and all changes coming within the equivalency range of the invention are intended to be embraced in the scope of the invention.

INDUSTRIAL APPLICABILITY

As apparent from the above description, the present invention is applicable to a transmitter and a receiver for use in a communication system. 

What is claimed is:
 1. A user equipment for supporting multiple component carriers through carrier aggregation, comprising: a processor configured to determine a maximum transmission power P_(MAX,PUCCH) of physical uplink control channel (PUCCH) and a maximum transmission power P_(MAX,PUSCH) of physical uplink shared channel (PUSCH) for a component carrier x among the multiple component carriers; and a radio frequency (RF) unit, coupled to the processor, configured to transmit the PUCCH and the PUSCH on the component carrier x, wherein the RF unit is further configured to receive control information associated with respective maximum allowed powers for the multiple component carriers, wherein the maximum transmission power P_(MAX,PUCCH) is set to be P_(PMAX,x), where P_(MAX,x) is a maximum allowed power for the component carrier x, and wherein the maximum transmission power P_(MAX,PUSCH) is set to be ‘P_(MAX,x)-P_(PUCCH)’, where P_(PUCCH) is a transmission power of the PUCCH.
 2. The user equipment of claim 1, wherein the processor is further configured to determine the transmission power P_(PUCCH) of the PUCCH within the maximum transmission power P_(MAX,PUCCH); and a transmission power P_(PUSCH) of the PUSCH within the maximum transmission power P_(MAX,PUSCH).
 3. The user equipment of claim 2, wherein the RF unit is configured to transmit the PUCCH at the transmission power P_(PUCCH) and the PUSCH at the transmission power P_(PUSCH) on the component carrier x simultaneously.
 4. The user equipment of claim 3, further comprising: a plurality of antennas, wherein the RF unit is further configured to receive information indicating one or more antennas to be turned on or turned off and to transmit the PUCCH and the PUSCH through one or more antennas turned on.
 5. The user equipment of claim 1, wherein the multiple component carriers share a maximum transmission power P_(MAX) of the user equipment.
 6. The user equipment of claim 1, wherein the component carrier x is a primary component carrier among the multiple component carriers.
 7. A method for transmitting uplink signal at a user equipment supporting multiple component carriers through carrier aggregation, comprising: receiving control information associated with respective maximum allowed power for the multiple component carriers; determining a maximum transmission power P_(MAX,PUCCH) of a physical uplink control channel (PUCCH) and a maximum transmission power P_(MAX,PUSCH) of a physical uplink shared channel (PUSCH) for a component carrier x among the multiple component carriers based on a maximum allowed power for the component carrier x among the respective maximum allowed power for the multiple component carriers; and transmitting the PUCCH and the PUSCH on the component carrier x, wherein the method further comprises: receiving control information associated with a maximum allowed power for each of the multiple component carriers, wherein the maximum transmission power P_(MAX,PUCCH) is set to be P_(MAX,x), where P_(MAX,x) is the maximum allowed power for the component carrier x, and wherein the maximum transmission power P_(MAX,PUSCH) is set to be ‘P_(MAX,x)-P_(PUCCH)’, where P_(PUCCH) is a transmission power of the PUCCH.
 8. The method of claim 7, further comprising: determining the transmission power P_(PUCCH) of the PUCCH within the maximum transmission power P_(MAX,PUCCH); and determining a transmission power P_(PUSCH) of the PUSCH within the maximum transmission power P_(MAX,PUSCH).
 9. The method of claim 8, wherein transmitting the PUCCH and the PUSCH comprises transmitting the PUCCH at the transmission power P_(PUCCH) and the PUSCH at the transmission power P_(PUSCH) on the component carrier x simultaneously.
 10. The method of claim 9, wherein the user equipment includes a plurality of antennas, and the method further comprises: receiving information indicating one or more antennas of the plurality of antennas to be turned on or turned off; and transmitting the PUCCH and the PUSCH through one or more antennas turned on.
 11. The method of claim 7, wherein the multiple component carriers share a maximum transmission power P_(MAX) of the user equipment.
 12. The method of claim 7, wherein the component carrier x is a primary component carrier among the multiple component carriers. 